At present, various electronic devices having a planar touch sensor arranged on the front side of a display screen are being contrived. Such a touch sensor has, as an operation input function, a drag and drop function.
For instance, as illustrated in the electronic device of Patent Literature 1, the drag and drop function uses a pressing force onto the touch sensor.
The electronic device of Patent Literature 1 detects that a pressing force onto an operation surface is a threshold value or more, and selects the object assigned to the detection position. At detecting movement of the touch position with the pressing force detected, movement of the object is started. That is, the drag operation is started.
While the drag speed is a predetermined value or more, pressing force detection is stopped, and when the drag speed is less than the predetermined value, pressing force detection is started again. At detecting that the pressing force is less than the threshold value, the position of the object is determined. That is, the drop operation is performed.
Patent Literature 1: Japanese Patent Application Laid-Open (JP-A) No. 2012-53926
However, in the conventional structure and process, the following problems arise. FIG. 7 illustrates waveform graphs for explaining the problems of the conventional structure and process. FIG. 7 illustrates the time waveforms of the moving speed, the pressing force, and the touch detection flag in a detection position.
In selecting an object displayed on the operation surface with a finger, the operator who lightly touches the operation surface with the finger slowly moves the finger sometimes. In this case, the operator can unintentionally press the operation surface. For instance, as illustrated in the example in FIG. 7, even in the section in which the moving speed in the operation position is low, the pressing force becomes stronger.
After such pressing, as illustrated in FIG. 7, the pressing force is threshold value Thc or more, the touch detection flag is changed from Low to Hi to start the drag operation. This position is detection drag position Pd. However, for instance, as illustrated in FIG. 7, the operator often increases the moving speed of the finger in the operation position after the finger reaches target drag position Pp. Detection drag position Pd does not coincide with target drag position Pp, with the result that the non-target object is dragged.
When threshold value Thc is set sufficiently high, such an unintentional drag operation can be prevented. However, in this case, unless pressing exceeding threshold value Thc which is set high is performed, the drag operation cannot be started. Consequently, the operability is lowered.